Following doctor's orders

Years ago when I wanted to lose weight after having my kids my doctor told me to stop the fad diets (Atkins, Slim Fast, hot dog diet, you name it chances are I tried it). She told me instead to have (4) 400 calorie meals (1600 calories) and a 200 calorie snack for a total of 1800 calories a day. Chocolate was my thing so she said to buy the minis, keep em in the freezer and have 1 serving per day. She also said to always have a carb with protein and never on its own and that if I screw up a meal then I screw up a meal, can't undo it, just move on. If I had too much pizza on a friday dont say "I ruined my diet, now I will do what I want and start over on Monday," just eat the next meal as planned. Exercise doing something I enjoy for an hour a day. She told me if I did this I will lose a steady 2 lbs a week which in fact I did. I never felt starved or stressed over the "diet" issue, I never felt like a failure because I got carried away with a meal once in a while, and without fail I lost 2 lbs a week every week without ever hitting a plateau. I gained it all back plus some years later when the bad habits came back and now I'm fighting severe hypothyroidism due to thyroid cancer, thyroid removal, and treatment. I'm going back to my doctor's advice and seeing if once again I can have success on a sensible plan because at this point I'll take 2 lbs a week instead of 0 lbs per week. My new doctor is telling me weight loss is impossible the first year after a thyroidectomy. I may not be able to prove him wrong but maybe I can prevent this slow and steady gain that is trying to start once again.